Processor Status Register

The Processor Status Register (P) is on the 65c816 and contains several flags:

• Negative Flag - N
• Overflow Flag - V
• Memory/Accumulator Select - M
• Index Register Select - X
• Decimal Mode - D
• Interrupt Disable Flag - I
• Zero Flag - Z
• Carry Flag - C

It can be pulled from the stack via PLP and RTI.

There are nine instructions that directly modify these flags, including:^[3]

• REP
• SEP
• CLC
• SEC
• CLD
• SED
• CLI
• SEI
• CLV

The only transfer instructions that do not modify these flags are TCS and TXS.

See Also

• Program Status Word
• DSP1 Status Register
• PHP

References

1. Table 18.2 Eyes & Lichty, page 422: https://archive.org/details/0893037893ProgrammingThe65816/page/422
2. Figure 17.3, Lbid, page 377: https://archive.org/details/0893037893ProgrammingThe65816/page/377
3. page 262, https://archive.org/details/0893037893ProgrammingThe65816/page/n288